Protecting Your IP When Sharing Engineering Drawings with Contract Manufacturers

Every time an OEM shares engineering drawings with a contract manufacturer, fabrication shop, or machining supplier, they face a tradeoff: the supplier needs enough information to quote and produce the part, but not so much information that they could contact your customer directly, quote your customer in the future without you, or understand your proprietary system architecture.

This is a real risk. Supply chain IP disputes are common in aerospace, defense, automotive, medical devices, and industrial manufacturing. A drawing package that reveals your customer's name, program, and internal part numbering convention gives a supplier enough information to approach that customer independently.

What to redact before sending

• The title block is where most leakage happens. Standard engineering title blocks contain:
• Company/client name (the OEM's customer, or the OEM itself)
• Project or program name
• Internal part number
• Drawn-by name and contact
• Revision history with project dates
• Drawing number that encodes product family

• Proprietary notes often contain:
• Material specifications that reveal design intent
• Process requirements that describe proprietary techniques
• Reference to other parts that reveal assembly context

• What you can leave:
• Part geometry and dimensions (the supplier needs these)
• Tolerance and surface finish requirements (needed for quoting)
• General material callouts (aluminum, stainless, etc.)

The white-rectangle problem

Most engineers reach for their PDF editor's "delete" or "redact" function and cover the sensitive area with a white box. This looks right on screen, but many PDF viewers allow users to select text under a white rectangle — it's still in the file. Some automated tools can extract it.

Black-bar redaction on supported native text removes the text from the PDF content stream, then draws an opaque black bar on top. Always review the export before sharing — especially for scanned pages, form fields, or layered PDFs.

The Find & Redact All workflow for drawing packages

If a drawing package has 30 sheets and the customer name appears in every title block, you don't want to redact them one by one.

1. Upload the drawing PDF (landscape ARCH D or E sheets auto-scale to fit)
2. Press Ctrl+F, type the customer name
3. See all 30 instances highlighted across all sheets
4. Click Redact All — done in one click
5. Repeat for the program name, internal part number, and engineer contact

Typical time for a 30-sheet drawing package with 3–4 sensitive terms: under 5 minutes.

By industry

Aerospace & defense: Customer identity (often the prime contractor) must be protected from sub-tier suppliers. Program names may be controlled or ITAR-relevant.

Automotive: Vehicle platform and model year are typically confidential until announcement. OEMs require suppliers to maintain confidentiality of tooling drawings.

Medical devices: Device identification and intended use must be restricted. FDA submissions reference device details that competitors should not see.

Electronics/PCB: Circuit function notes and component selection reveal design intent. Customer identity on schematics sent to board houses must be removed.

Oil & gas: Operator identity and field location must be protected when sending to machining and fabrication shops. Facility names appear in drawing titles.

A note on NDAs

NDAs provide legal recourse after a breach — they don't prevent it. Removing the identifying information from the drawing before distribution is a first-line technical control, not a substitute for an NDA. Use both.

Team workflows

If multiple engineers are preparing drawing packages, PDFAmend team plans ($19.99/month for 5 users) give everyone unlimited access to the redaction workflow without per-seat billing or license management overhead.